One known way of recognizing and verifying a user in various systems, such as computer systems or telephone systems, is to utilize the speech signal. All such speaker recognition systems attempt to find speech parameters for automatically recognizing the speaker and distinguishing different speakers from each other. A sample derived from the speech of each speaker is used to create models containing certain parameters characteristic of the voice, and the models are then stored in the memory of the speaker recognition system. To recognize an anonymous speaker, his or her speech signal is sampled and a model comprising the same parameters is created from the speech samples and compared with reference models or templates stored in the memory of the system. If the model created from the speech signal to be identified matches with one of the templates of known speakers stored in the memory with sufficient accuracy when applying a predetermined criterion, the anonymous speaker is recognized as the person from whose speech signal the matching template had been created. Generally speaking, this is the main principle in all known speaker recognition systems, whereas the parameters and solutions used for modelling the speaker's voice deviate greatly from each other. Examples of known speaker recognition methods and systems are disclosed in U.S. Pat. Nos. 4,720,863 and 4,837,830, GB Patent Application 2 169 120 and EP Patent Application 0 369 485.